转炉炼钢熔池流动特征规律研究

BOF is the main method of steelmaking currently. Top blowing oxygen and bottom blowing agitation is the core process of BOF steelmaking, which can influence the resource consumption and product quality directly. Generally, the parameters of top and bottom blowing are calculated by the theoretical or empirical formula based on normal temperature and pressure environment. However the BOF steelmaking is high temperature melting process. The oxygen jet is wrapped by high temperature flue gas, and the bottom blown nozzle is heated by the molten bath and refractory, which leads to the difference between research and reality. The difference has a bad effect on the rhythm, quality and cost of steelmaking. This paper use numerical simulation and hydraulic simulation method to develop a three-dimensional multiphase flow model. This paper makes oxygen blowing experiment in steelmaking temperature and pressure, and verifies the influence of injection parameters on metallurgical reactions through 500kg converter. This topic reveals the morphology of cavity in high temperature environment, describes the flow phenomena in converter correctly, and determines the relationship between the flow characteristics of converter bath and the rate of dephosphorization, decarburization, heating, lining erosion. This topic will provide data support for the design and optimizing of BOF injection parameters.

转炉炼钢是目前主要的炼钢方法，供氧及底吹搅拌是转炉炼钢的核心工艺，直接影响到冶炼过程的资源消耗和产品质量。通常转炉顶吹供氧及底吹搅拌工艺参数由常温常压条件下的理论或经验公式计算得到，但转炉炼钢是高温熔炼过程，氧气射流被高温烟气包裹，底吹喷嘴受熔体和耐火材料加热，现有研究结果与实际流股特性偏差较大，对炼钢生产的节奏、质量、成本造成不利影响。本课题采用数值模拟和水力学模拟研究方法，基于全尺寸数值模拟架构和相似理论，建立高温、变压条件下的三维全尺寸“气-渣-金”三相流耦合模型；基于变温-变压转炉环境模拟仓，使用动压实时捕捉、高温热成像等手段完成射流喷吹热态实验；通过500kg转炉热态实验，验证喷吹参数对冶金反应的影响规律。课题探明高温环境中射流冲击凹坑的形貌，准确描述转炉熔池流动现象，确定转炉熔池流动特征指数和熔池脱磷、脱碳、升温、炉衬侵蚀速率之间的关系，为转炉喷吹工艺参数设计优化提供数据支撑。

转炉炼钢是目前主要的炼钢方法，供氧及底吹搅拌是转炉炼钢的核心工艺，直接影响到冶炼过程的资源消耗和产品质量。通常转炉顶吹供氧及底吹搅拌工艺参数由常温常压条件下的理论或经验公式计算得到，但转炉炼钢是高温熔炼过程，氧气射流被高温烟气包裹，底吹喷嘴受熔体和耐火材料加热，现有结果与实际流股特性偏差较大，对炼钢生产的节奏、质量、成本造成不利影响。本课题系统深入地研究了环境温度、环境压力和氧气滞止温度对单流股及多流股超音速氧气射流特性的影响规律，探明了转炉炼钢炉膛内多孔超音速氧枪喷头的流场特性；首次提出并研究了基于特征线法的拉瓦尔喷管设计方法，通过优化喷管型面设计，进一步提升了氧枪喷头的冶金效能；建立了转炉底吹元件的流-固耦合传热模型，研究了底吹气流在喷枪内的流动规律，以及底吹气泡在液相中上浮的形貌变化；建立了转炉炼钢的三维全尺寸数值模型和相似缩小的水力学模型，研究了炼钢温度下多流股超音速氧气射流冲击熔池所形成的凹坑形貌特征，揭示了冲击深度、冲击面积与超音速射流相关喷吹参数之间的函数关系，探明了顶底复吹转炉“气-渣-金”三相耦合流动规律，并探索性地研究了预热式氧枪、旋流氧枪及侧吹喷枪对转炉熔池的冲击搅拌效果；首次将转炉流场与脱磷动力学模型耦合，初步研究了吹炼工艺对转炉脱磷过程的影响规律；最后，提出了转炉熔池流动特征指数概念，用于修正基于炉气分析的终点碳含量预报模型，建立了熔池流动与脱碳速率之间的有机联系。本项目对顶底复吹转炉的射流特征、熔池流场及冶金反应等复杂问题进行了系统研究，有助于转炉炼钢提高钢水质量、降低生产成本、加快冶炼节奏，为转炉炼钢喷吹参数的设计和优化提供了理论依据。